fix(codeagent-wrapper): add worker limit cap and remove legacy alias

- Add maxParallelWorkersLimit=100 cap for CODEAGENT_MAX_PARALLEL_WORKERS
- Remove scripts/install.sh (codex-wrapper legacy alias no longer needed)
- Fix README command example: /gh-implement -> /gh-issue-implement
- Add TestResolveMaxParallelWorkers unit test for limit validation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

codeagent-wrapper/config.go

@@ -249,6 +249,8 @@ func parseArgs() (*Config, error) {
 	return cfg, nil
 }
 
+const maxParallelWorkersLimit = 100
+
 func resolveMaxParallelWorkers() int {
 	raw := strings.TrimSpace(os.Getenv("CODEAGENT_MAX_PARALLEL_WORKERS"))
 	if raw == "" {
@@ -261,5 +263,10 @@ func resolveMaxParallelWorkers() int {
 		return 0
 	}
 
+	if value > maxParallelWorkersLimit {
+		logWarn(fmt.Sprintf("CODEAGENT_MAX_PARALLEL_WORKERS=%d exceeds limit, capping at %d", value, maxParallelWorkersLimit))
+		return maxParallelWorkersLimit
+	}
+
 	return value
 }